1. Field of the Invention
This invention relates to a screw-on throat plug assembly for use in a closed loop dispensing system or other types of dispensing systems and more particularly to a dispensing system for dispensing corrosive liquid chemicals or dangerous medical liquid products which are typically drawn from a container such as a bottle or the like to a mixing machine or the like. Even more particularly, this invention relates to a closed loop dispensing system including a mechanical venting means for a throat plug assembly which is screwed onto the throat of a liquid container.
2. Description of the Related Art
Corrosive liquid chemicals and dangerous medical liquid products are typically contained in a container such as a bottle or the like and are frequently dispensed therefrom to a mixing machine. Normally, a cap is placed on the bottle with a dip tube extending therefrom downwardly into the interior of the bottle for drawing the liquid upwardly thereinto. Normally, a dispensing tube extends from the cap to a mixing machine or to some other piece of equipment which creates suction in the dispensing tube to draw the liquid from the interior of the bottle.
Applicant has previously patented many closed loop dispensing systems with improved safety means and with improved venting. For example, see U.S. Pat. Nos. 5,988,456; 6,142,345; 6,968,983; and 8,083,107, the disclosures of which are incorporated herein by reference thereto to complete the disclosure, if necessary.
In Applicant's earlier U.S. Pat. No. 8,083,107 and in Applicant's other U.S. Pat. Nos. 6,968,983; 6,142,345; and 5,988,456, the throat plug assemblies thereof were press-fitted into the throats of the container. Although Applicant's earlier throat plug assemblies have met with considerable success, it has been found that the ability to threadably screw the throat plug assembly onto the externally threaded throat of the container is a distinct improvement over the throat plugs which were press-fitted into the throats of the containers. One disadvantage of the prior art throat plug assemblies is that the throat plug assemblies must be driven or forced downwardly into the throat of the container. Another disadvantage of the prior art throat plug assemblies is that it is difficult to remove the press-fitted throat plug assemblies from the throat of the container once the liquid therein has been dispensed from the container so that the container may be refitted and used again.